The present invention relates to a thermocouple instrument and, more particularly, to a thermocouple instrument having a structure capable of enduring a vigorous vibration and impact.
A conventional thermocouple instrument which has been heretofore used, for example, in an aircraft engine to measure the temperature of the engine itself or of exhaust gas from the engine employed, to endure high temperature and corrosive atmosphere, a structure in which a thermocouple element formed of two dissimilar conductors joined at the ends was mounted together with an insulating powder in an inner metal protecting tube which was further mounted in an outer metal protecting tube. In order to avoid a loss responsiveness in detecting the temperature in such a structure, an air gap was normally provided in the end part of the outer metal protecting tube and a pair of small holes were formed at both side surfaces of the ends of the protecting tube, and gas to be measured at its temperature flowed through the small holes in the air gap.
When this thermocouple instrument was used to measure the temperature of the aircraft engine itself or of the exhaust gas of the engine, the thermocouple instrument was exposed to vigorous vibration and impact. When the thermocouple instrument thus constructed was exposed to such severe vibration and impact, the inner and outer metal protecting tubes came into violent contact with each other and were resultantly damaged. Therefore, various trials of fixedly securing both the outer and inner protecting tube have been heretofore carried out. However, the attachment has not been sufficient, additional members have been required, and the structure of the instrument has thus been complicated, resulting in a difficulty in securing both the outer and inner protecting tubes.